Apparatus for entraining and removing fines from conical milis



Apr.3,1923.

H. W. HARDlNGE APPARATUS FOR ENTRAINING AND REMOVING FINES FROM CONICALMILLS Fil ed Apr. 29, 1920 INVENTOR %& ATTORNEYS Patented Apr. 3, 1923.

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HARRY W. HARDINGE, OF NEW YORK, N. Y.

APPARATUS FOR ENTRAINING AN'D REMOVING FINES FROM CONICAL MILLS.

Application filed April 29, 1920. Serial No. 377,489.

To all whom it may concern Be it known that I, HARRY W. HARDINGE, acitizen of the United States, residing at New York, county and State ofNew York, have'invented certain new and useful Improvements in Apparatusfor Entraining and Removing Fines from Conical Mills, of which thefollowing is a full, clear, and exact description.

This invention relates to a process of and apparatus for grinding ordisentegrating cement, coal, ores or other materials.

I Conical mills are now well known in the art (see for example, amongother patents, my U. S. Patent No. 908,861) and may be somewhatgenerally described as follows. Such mills comprise a drum having aninlet opening or openings, a conical outlet ortion and an outlet opemngor openings. he

conical outlet portion performs important functions. It is by virtue ofthis portion that the material is automatically classified according tosize by the rotation of the mill. In this classification the coarsermaterial lies toward or adjacent the inlet of the mill and the particlesof material diminish in size toward the apex of the cone shaped portion.In other words, because of the inherent classifying action of the millthe fines travel automatically toward the apex of the cone leaving thecoarser particles behind until they are reduced to thedesired degree offineness.

One of the principal objects of the present invention is to provide amethod of and apparatus for aiding the above described inherentclassifying action of conical mills. Stated somewhat generically theinvention comprises employing the conical outlet or a portion thereof asa conduit through which a current of elastic fluid is directed towardthe outlet opening from the inside of the drum. Numerous importantfunctions flow from this feature as will hereinafter appear. The methodor process may perhaps best be described by more or less detailedconsideration of some of the forms of apparatus by which it may becarried out.

eferri'ng to the drawings which illustrate what I now consider preferredphysical embodiments of my invention:

Fig. 1 is a somewhat diagrammatic view illustrating one form of myinvention.

Fig. 2 is a similar view illustrating a modification.

Calling attention to Fig. 1 the conical mill there illustrated comprisesa drum 1 rotatably mounted; in bearings 5, 6 and which may berotatedabout its longitudinal axis by any suitable means (not shown).The drum 1 is provided with ing 3 through which'material to be groundmay be fed and an outlet opening 4 through which the ground material isdischarged. By virtue of the conical outlet portion 2 rotation of thedrum not only causes disintegration of the material but the material isautomatically classified according to size as above described and asindicated more or less diagrammatically in Fig. 1. It is important, forvarious reasons, that the material be removed from the drum with theutmost despatch so soon as it is reduced to the desired degree offineness. Some of the more important of these reasons may be stated asfollows. Any fines Within the mill are so much dead weight and'increasethe power required to rotate the mill. Fines withinthe mill also serveas a cushion and the larger particles of material do not receive thefull disintegration-causing impact during the rotation of the mill. Theproblem of removing the fines as soon as possible after they are formed(or in other words aiding the inherent classifying action of the mill)is rendered somewhat difficult dueto the fact that the amount of finesincreases towards the apex of the cone 2.

In accordance with my invention I cause a current of elastic motivefluid to enter the drum through a suitable inlet opening or openingswhich current then flows through the conical outlet toward the apexthereof and out through an outlet 0 ening or openings. One way ofeffecting t is result is illustrated in Fig. 1. The outlet opening 4 ofthe mill is employed as the outlet opening for the fluid stream and theflow or current is created by creating a negative pressure or suction atsaid outlet 4 by any suitable means. One form of such means isillustrated in the last mentioned figure and may be constructed asfollows.

an inlet openhe outlet 4 communicates with a stationary conduit orpassage 7 provided with a converging portion 8 and a motive fluid inlet11 terminating in a nozzle 10. It will be appreciated that the elements10, 11 and 8 constitute an ejector and .by introducing motive fluid suchas gas or liquid or mixture of the same under pressure through thenozzle 10, a negative pressure or suction will be created at the opening4. As the opening 3 is Wholly or partially open to atmosphere a streamof air will enter the through the conical outlet indicated in thedrawtrained in the current and carried with it through the outlet 4.Furthermore those of the fines brought to the surface of the materialare entrained and carried out in the same way. In addition the fluidcurrent or stream penetrates the mass of material to a certain extent,assing between the interstices, thereby dislodging fines and entrainingthem. lhe fines are discharged at the outlet 9 of the ejector.

It will be noted that the amount of fines carried or propelled by thefluid stream within the mill increases in the direction of the apex ofthe mill. It is therefore important that the velocity of the fluidstream, and consequently its entraining and carrying power, shouldincrease in the direction of the outlet 4. Hearing in mind that thevelocity at any point of a stream is inversely proportional to thecross-section of the stream at that point, it will be seen that thevelocit cone 2 is east at the base of the cone and increases as the apexis approached. The velocity is greatest at the outlet 4 so that thecurrent possesses the necessary entraining and removing power at thispoint although its velocity at the base of the cone 2 may be only thatrequired to entrain and remove the relatively small amount of fines.

Instead of, or in addition to, creating a negative pressure or suctionat the outlet 4 in order to pass same result may be attained by forcingelastic fluid into the drum through a suitable The elements 1, 2, 3 and4 correspond to I those similarly designated in Fig. 1 and need nofurther description. Air or other elastic fluid under pressure isintroduced through a. stationary pipe 12 which discharges below thesurface of the. material at a point spaced from the outlet opening 4..This passage of motive fluid upwardly through the material dislodges anyfines which may adhere to the larger particles of material and the finesare discharged through the opening 4 through which the current of motivefluid passes. While the means 12 may be relied on to establish a currentof elastic fluid portion 2 and opening 4 by substantially that theelastic motive fluid ot' the fluid passing through the.

the current of elastic fluid 'through the outlet portion 2, broadly thethrough the outlet closing the inlet 3, I prefer to provide anadditional source of fluid shown as a. jet 14 supplied with fluid underressure through a stationary conduit 15. It will be noted under pressureis in effect discharged within the mill at or ad'acent the base of theconical outlet of the mi 1. A fan or blower F, or other suitable sourceof elastic fluid may be employed to supply the jets of nozzles throughthe pipes 12 and 15. The said jet is directed toward the outlet openingand together with the converging port-ion 2 of the rotatable drum 1forms an ejector whose outlet is at 4. By virtue of the structuredescribed the fines within the mill are entrained and removed from themill b a fluid stream of increasing velocity towar the apex of the cone.desirable a plurality of lifting vanes 16 may be provided within thecone portion 2 for the purpose of periodically elevating portions of thematerial and dropping the same into the more active portion of the fluidstream.

In accordance with the provisions of the patent statutes, I have hereindescribed the principles of operation of my invention, together with theapparatus which I new consider to represent the best embodimentsthereofbut I desire to have it understood that the apparatus shown is onlyillustrative and that the invention can be carried out b other means.Also, while it is designe to use the various features and elements inthe combinations and relations described, some of these may be alteredand others omitted and some of the features of each modification may beembodied in the other without interfering with the more general resultsand effects outlined, and the invention extends to such use.

It will be understood of coursethat the mills embodying the presentinvention may be provided with any suitable grinding media and withother desirable" appurtenances and auxiliary devices well known in theart.

What I claim is:

The combination with a conical grinding mill comprising a rotatable drumhaving a conical outlet portion for automatically classifying materialaccording to size, provided with an outlet opening for dischargting thematerial when ground, of ajet which discharges into said conical outletportion adjacent the base thereof and directed toward said outletopening, said jet and conical outlet portion cooperating to form anejector and means for supplying elastic motive fluid to said jet underpres sure.

In testimony whereof I hereto afiix my signature.

HARRY W. HAR-DINGE.

